It’s easy to appreciate the seasonality of winter blues, but web searches show that other disorders may ebb and flow with the weather as well.

Google searches are becoming an intriguing source of health-related information, exposing everything from the first signs of an infectious disease outbreak to previously undocumented side effects of medications. So researchers led by John Ayers of the University of Southern California decided to comb through queries about mental illnesses to look for potentially helpful patterns related to these conditions. Given well known connections between depression and winter weather, they investigated possible connections between mental illnesses and seasons.

Using all of Google’s search data from 2006 to 2010, they studied searches for terms like “schizophrenia” “attention deficit/hyperactivity disorder (ADHD),” “bulimia” and “bipolar” in both the United States and Australia. Since winter and summer are reversed in the two countries finding opposing patterns in the two countries’ data would strongly suggest that season, rather than other things that might vary with time of year, was important in some way in the prevalence of the disorders.

“All mental health queries followed seasonal patterns with winter peaks and summer troughs,” the researchers write in their study, published in the American Journal of Preventive Medicine. They found that mental health queries in general were 14% higher in the winter in the U.S. and 11% higher in the Australian winter.

The seasonal timing of queries regarding each disorder was also similar in the two countries. In both countries, for example, searches about eating disorders (including anorexia and bulimia) and schizophrenia surged during winter months; those in the U.S. were 37% more likely and Australians were 42% more likely to seek information about these disorders during colder weather than during the summer. And compared to summer searches, schizophrenia queries were 37% more common in the American winter and 36% more frequent during the Australian winter. ADHD queries were also highly seasonal, with 31% more winter searches in the U.S. and 28% more in Australia compared to summer months.

Searches for depression and bipolar disorder, which might seem to be among the more common mental illnesses to strike during the cold winter months, didn’t solicit as many queries: there were 19% more winter searches for depression in the U.S. and 22% more in Australia for depression. For bipolar, 16% more American searches for the term occurred in the winter than in the summer, and 18% more searches occurred during the Australian winter. The least seasonal disorder was anxiety, which varied by just 7% in the U.S. and 15% in Australia between summer and winter months.

Understanding how the prevalence of mental illnesses change with the seasons could lead to more effective preventive measures that alert people to symptoms and guide them toward treatments that could help, say experts. Previous research suggests that shorter daylight hours and the social isolation that accompanies harsh weather conditions might explain some of these seasonal differences in mental illnesses, for example, so improving social interactions during the winter months might be one way to alleviate some symptoms. Drops in vitamin D levels, which rise with exposure to sunlight, may also play a role, so supplementation for some people affected by mood disorders could also be effective.

The researchers emphasize that searches for disorders are only queries for more information, and don’t necessarily reflect a desire to learn more about a mental illness after a new diagnosis. For example, while the study found that searches for ‘suicide’ were 29% more common in winter in America and 24% more common during the colder season in Australia, other investigations showed that completed suicides tend to peak in spring and early summer. Whether winter queries have any relationship at all to spring or summer suicides isn’t clear yet, but the results suggest a new way of analyzing data that could lead to better understanding of a potential connection.

And that’s the promise of data on web searches, says the scientists. Studies on mental illnesses typically rely on telephone or in-person surveys in which participants are asked about symptoms of mental illness or any history with psychological disorders, and people may not always answer truthfully in these situations. Searches, on the other hand, have the advantage of reflecting people’s desire to learn more about symptoms they may be experiencing or to improve their knowledge about a condition for which they were recently diagnosed. So such queries could become a useful resource for spotting previously undetected patterns in complex psychiatric disorders. “The current results suggest that monitoring queries can provide insight into national trends on seeking information regarding mental health, such as seasonality…If additional studies can validate the current approach by linking clinical symptoms with patterns of search queries,” the authors conclude, “This method may prove essential in promoting population mental health.”